MvvmCross.Plugin.BLE 3.0.0

There is a newer prerelease version of this package available.
See the version list below for details.
dotnet add package MvvmCross.Plugin.BLE --version 3.0.0
NuGet\Install-Package MvvmCross.Plugin.BLE -Version 3.0.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="MvvmCross.Plugin.BLE" Version="3.0.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add MvvmCross.Plugin.BLE --version 3.0.0
#r "nuget: MvvmCross.Plugin.BLE, 3.0.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install MvvmCross.Plugin.BLE as a Cake Addin
#addin nuget:?package=MvvmCross.Plugin.BLE&version=3.0.0

// Install MvvmCross.Plugin.BLE as a Cake Tool
#tool nuget:?package=MvvmCross.Plugin.BLE&version=3.0.0

<img src="icon_small.png" width="71" height="71"/> Bluetooth LE plugin for Xamarin & MAUI

Build status: Build status

Xamarin, MAUI and MvvMCross plugin for accessing the bluetooth functionality. The plugin is loosely based on the BLE implementation of Monkey Robotics.

Important Note: With the term "vanilla" we mean the non-MvvmCross version, i.e. the pure Xamarin or MAUI plugin. You can use it without MvvmCross, if you download the vanilla package.

Support & Limitations

Release Notes

Platform Version Limitations
Xamarin.Android 4.3
Xamarin.iOS 7.0
Xamarin.Mac 10.9 (Mavericks) >= 2.1.0
Xamarin.UWP 1709 - 10.0.16299 >= 2.2.0
MAUI (all 4 OS) >= 3.0.0

Nuget Packages

package stable beta downloads
Plugin.BLE NuGet NuGet Beta Downloads
MvvmCross.Plugin.BLE NuGet MvvMCross NuGet MvvMCross Beta Downloads

Installation

Vanilla

// stable
Install-Package Plugin.BLE
// or pre-release
Install-Package Plugin.BLE -Pre

MvvmCross

Install-Package MvvmCross.Plugin.BLE
// or
Install-Package MvvmCross.Plugin.BLE -Pre

Android

Add these permissions to AndroidManifest.xml. For Marshmallow and above, please follow Requesting Runtime Permissions in Android Marshmallow and don't forget to prompt the user for the location permission.

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />

Android 12 and above may require one or more of the following additional runtime permissions, depending on which features of the library you are using (see the android Bluetooth permissions documentation)

<uses-permission android:name="android.permission.BLUETOOTH_SCAN" />
<uses-permission android:name="android.permission.BLUETOOTH_CONNECT" />
<uses-permission android:name="android.permission.BLUETOOTH_ADVERTISE" />

Add this line to your manifest if you want to declare that your app is available to BLE-capable devices only:

<uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>

iOS

On iOS you must add the following keys to your Info.plist

<key>UIBackgroundModes</key>
<array>
    
    <string>bluetooth-central</string>

    
    <string>bluetooth-peripheral</string>
</array>


<key>NSBluetoothPeripheralUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>


<key>NSBluetoothAlwaysUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>

MacOS

On MacOS (version 11 and above) you must add the following keys to your Info.plist:

<key>NSBluetoothAlwaysUsageDescription</key>
<string>YOUR CUSTOM MESSAGE</string>

UWP

Add this line to the Package Manifest (.appxmanifest):

<DeviceCapability Name="bluetooth" />

Sample app

We provide a sample Xamarin.Forms app, that is a basic bluetooth LE scanner. With this app, it's possible to

  • check the ble status
  • discover devices
  • connect/disconnect
  • discover the services
  • discover the characteristics
  • see characteristic details
  • read/write and register for notifications of a characteristic

Have a look at the code and use it as starting point to learn about the plugin and play around with it.

Usage

Vanilla

var ble = CrossBluetoothLE.Current;
var adapter = CrossBluetoothLE.Current.Adapter;

MvvmCross

The MvvmCross plugin registers IBluetoothLE and IAdapter as lazy initialized singletons. You can resolve/inject them as any other MvvmCross service. You don't have to resolve/inject both. It depends on your use case.

var ble = Mvx.Resolve<IBluetoothLE>();
var adapter = Mvx.Resolve<IAdapter>();

or

MyViewModel(IBluetoothLE ble, IAdapter adapter)
{
    this.ble = ble;
    this.adapter = adapter;
}

Please make sure you have this code in your LinkerPleaseLink.cs file

public void Include(MvvmCross.Plugins.BLE.Plugin plugin)
{
    plugin.Load();
}

IBluetoothLE

Get the bluetooth status
var state = ble.State;

You can also listen for State changes. So you can react if the user turns on/off bluetooth on your smartphone.

ble.StateChanged += (s, e) =>
{
    Debug.WriteLine($"The bluetooth state changed to {e.NewState}");
};

IAdapter

Scan for devices
adapter.DeviceDiscovered += (s,a) => deviceList.Add(a.Device);
await adapter.StartScanningForDevicesAsync();
Scan Filtering
var scanFilterOptions = new ScanFilterOptions();
scanFilterOptions.ServiceUuids = new [] {guid1, guid2, etc}; // cross platform filter
scanFilterOptions.ManufacturerDataFilters = new [] { new ManufacturerDataFilter(1), new ManufacturerDataFilter(2) }; // android only filter
scanFilterOptions.DeviceAddresses = new [] {"80:6F:B0:43:8D:3B","80:6F:B0:25:C3:15",etc}; // android only filter
await adapter.StartScanningForDevicesAsync(scanFilterOptions);
ScanTimeout

Set adapter.ScanTimeout to specify the maximum duration of the scan.

ScanMode

Set adapter.ScanMode to specify scan mode. It must be set before calling StartScanningForDevicesAsync(). Changing it while scanning, will not affect the current scan.

Connect to device

ConnectToDeviceAsync returns a Task that finishes if the device has been connected successful. Otherwise a DeviceConnectionException gets thrown.

try
{
    await _adapter.ConnectToDeviceAsync(device);
}
catch(DeviceConnectionException e)
{
    // ... could not connect to device
}
Connect to known Device

ConnectToKnownDeviceAsync can connect to a device with a given GUID. This means that if the device GUID is known, no scan is necessary to connect to a device. This can be very useful for a fast background reconnect. Always use a cancellation token with this method.

  • On iOS it will attempt to connect indefinitely, even if out of range, so the only way to cancel it is with the token.
  • On Android this will throw a GATT ERROR in a couple of seconds if the device is out of range.
try
{
    await _adapter.ConnectToKnownDeviceAsync(guid, cancellationToken);
}
catch(DeviceConnectionException e)
{
    // ... could not connect to device
}
Get services
var services = await connectedDevice.GetServicesAsync();

or get a specific service:

var service = await connectedDevice.GetServiceAsync(Guid.Parse("ffe0ecd2-3d16-4f8d-90de-e89e7fc396a5"));
Get characteristics
var characteristics = await service.GetCharacteristicsAsync();

or get a specific characteristic:

var characteristic = await service.GetCharacteristicAsync(Guid.Parse("d8de624e-140f-4a22-8594-e2216b84a5f2"));
Read characteristic
var bytes = await characteristic.ReadAsync();
Write characteristic
await characteristic.WriteAsync(bytes);
Characteristic notifications
characteristic.ValueUpdated += (o, args) =>
{
    var bytes = args.Characteristic.Value;
};

await characteristic.StartUpdatesAsync();

Get descriptors
var descriptors = await characteristic.GetDescriptorsAsync();
Read descriptor
var bytes = await descriptor.ReadAsync();
Write descriptor
await descriptor.WriteAsync(bytes);
Get System Devices

Returns all BLE devices connected or bonded (only Android) to the system. In order to use the device in the app you have to first call ConnectAsync.


var systemDevices = adapter.GetSystemConnectedOrPairedDevices();

foreach(var device in systemDevices)
{
    await _adapter.ConnectToDeviceAsync(device);
}

Caution! Important remarks / API limitations

The BLE API implementation (especially on Android) has the following limitations:

  • Characteristic/Descriptor Write: make sure you call characteristic.WriteAsync(...) from the main thread, failing to do so will most probably result in a GattWriteError.
  • Sequential calls: Always wait for the previous BLE command to finish before invoking the next. The Android API needs its calls to be serial, otherwise calls that do not wait for the previous ones will fail with some type of GattError. A more explicit example: if you call this in your view lifecycle (onAppearing etc) all these methods return void and 100% don't guarantee that any await bleCommand() called here will be truly awaited by other lifecycle methods.
  • Scan with services filter: On specifically Android 4.3 the scan services filter does not work (due to the underlying android implementation). For android 4.3 you will have to use a workaround and scan without a filter and then manually filter by using the advertisement data (which contains the published service GUIDs).

Best practice

API

  • Surround Async API calls in try-catch blocks. Most BLE calls can/will throw an exception in certain cases, this is especially true for Android. We will try to update the xml doc to reflect this.
    try
    {
        await _adapter.ConnectToDeviceAsync(device);
    }
    catch(DeviceConnectionException ex)
    {
        //specific
    }
    catch(Exception ex)
    {
        //generic
    }
  • Avoid caching of Characteristic or Service instances between connection sessions. This includes saving a reference to them in your class between connection sessions etc. After a device has been disconnected all Service & Characteristic instances become invalid. Allways use GetServiceAsync and GetCharacteristicAsync to get a valid instance.

General BLE iOS, Android

  • Scanning: Avoid performing ble device operations like Connect, Read, Write etc while scanning for devices. Scanning is battery-intensive.
    • try to stop scanning before performing device operations (connect/read/write/etc)
    • try to stop scanning as soon as you find the desired device
    • never scan on a loop, and set a time limit on your scan

How to build the nuget package

  1. Build

    Open a console, change to the folder "dotnet-bluetooth-le/.build" and run cake.

  2. pack the nuget

    nuget pack ../Source/Plugin.BLE/Plugin.BLE.csproj

    nuget pack ../Source/MvvmCross.Plugins.BLE/MvvmCross.Plugins.BLE.csproj

Extended topics

How to contribute

We usually do our development work on a branch with the name of the milestone. So please base your pull requests on the currently open development branch.

Licence

Apache 2.0

Product Compatible and additional computed target framework versions.
.NET net6.0-android33.0 is compatible.  net6.0-ios16.1 is compatible.  net6.0-maccatalyst16.1 is compatible.  net6.0-windows10.0.19041 is compatible.  net7.0-android was computed.  net7.0-android33.0 is compatible.  net7.0-ios was computed.  net7.0-ios16.1 is compatible.  net7.0-maccatalyst was computed.  net7.0-maccatalyst16.1 is compatible.  net7.0-windows was computed.  net7.0-windows10.0.19041 is compatible.  net8.0-android was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-windows was computed. 
MonoAndroid monoandroid13.0 is compatible. 
Universal Windows Platform uap10.0.16299 is compatible. 
Xamarin.iOS xamarinios10 is compatible. 
Xamarin.Mac xamarinmac20 is compatible. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories (1)

Showing the top 1 popular GitHub repositories that depend on MvvmCross.Plugin.BLE:

Repository Stars
dotnet-bluetooth-le/dotnet-bluetooth-le
Bluetooth LE plugin for Xamarin/MAUI, supporting Android, iOS, Mac, Windows
Version Downloads Last updated
3.1.0-beta.3 54 3/25/2024
3.1.0-beta.2 69 2/12/2024
3.1.0-beta.1 964 11/17/2023
3.0.0 760 10/8/2023
3.0.0-rc.1 134 9/21/2023
3.0.0-beta.6 89 9/5/2023
3.0.0-beta.5 201 8/5/2023
3.0.0-beta.4 136 5/21/2023
3.0.0-beta.3 254 4/17/2023
3.0.0-beta.2 2,277 11/24/2022
3.0.0-beta.1 109 11/17/2022
2.2.0-pre5 567 7/11/2022
2.2.0-pre4 161 6/1/2022
2.2.0-pre2 1,914 9/17/2019
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2.1.3 3,226 5/1/2022
2.1.2 8,610 4/22/2021
2.1.1 33,813 8/28/2019
2.1.0 983 8/11/2019
2.1.0-pre1 423 8/4/2019
2.0.1 663 8/4/2019
2.0.0 1,741 8/3/2019
2.0.0-pre1 1,200 5/21/2018
1.3.0 15,618 7/23/2017
1.3.0-beta3 869 5/4/2017
1.3.0-beta2 779 4/27/2017
1.3.0-beta1 754 4/26/2017
1.3.0-alpha1 745 3/10/2017
1.2.3 1,513 4/18/2017
1.2.2 1,104 4/4/2017
1.2.1 1,297 3/8/2017
1.2.0 1,164 2/17/2017
1.2.0-beta4 853 12/23/2016
1.2.0-beta3 827 12/17/2016
1.2.0-beta2 831 11/27/2016
1.2.0-beta1 840 11/19/2016
1.1.0 1,378 10/21/2016
1.1.0-beta5 813 10/7/2016
1.1.0-beta4 785 10/2/2016
1.1.0-beta3 783 9/30/2016
1.1.0-beta2 986 9/21/2016
1.1.0-beta1 857 8/15/2016
1.0.0 1,841 8/7/2016
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1.0.0-beta3 838 6/3/2016
1.0.0-beta2 801 5/26/2016
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0.9.2 1,541 4/2/2016
0.9.1 1,331 3/18/2016
0.9.0 1,376 2/5/2016
0.9.0-beta3 1,692 1/15/2016
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0.9.0-beta1 1,237 12/15/2015
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0.8.6 1,386 10/26/2015
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0.8.4 1,383 10/22/2015
0.8.3 1,076 10/21/2015
0.8.2 1,656 9/14/2015
0.8.1 1,448 9/14/2015
0.8.0 1,430 9/14/2015
0.7.0 1,360 9/11/2015